VAST error codes / Linear and media errors
VAST error 405: Problem displaying media file
Short answer: A supported MediaFile was found but the player failed to display it.
What it means
The player picked a media file of a supported type but still could not play it: a codec, container, or metadata mismatch.
Common causes
- Unsupported codec inside a supported container
- MIME `type` that does not match the actual file
- Corrupt file or wrong reported dimensions/bitrate
How to fix it
Verify the declared `type` matches the real media, and that the codec is supported on the target device. Common in CTV and SSAI trafficking.
VAST error codes are runtime buckets emitted by the player. They tell you where the failure happened, not which line of XML caused it. Paste the raw tag into the validator to map this code onto the exact element and rule.
Related vastlint rules
- VAST-2.0-mediafile-type: <MediaFile> must have a type attribute
- VAST-2.0-mediafile-dimensions: <MediaFile> must have width and height attributes
Related error codes
Debug this tag now
Validate the XML, follow the wrapper chain, or check it in CI before launch:
# CLI: exits non-zero on errors, ideal for pipelines
vastlint check creative.xmlUse the right tool for this failure
If you already have the resolved XML, run a pure spec check. If you only have a live tag URL, test that endpoint first. If the failure happens in the wrapper chain, inspect each hop.